gamma correction


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gamma correction

(hardware)
Adjustments applied during the display of a digital representation of colour on a screen in order to compensate for the fact that the Cathode Ray Tubes used in computer monitors (and televisions) produce a light intensity which is not proportional to the input voltage. The light intensity is actually proportional to the input voltage raised to the inverse power of some constant, called gamma. Its value varies from one display to another, but is usually around 2.5.

Because it is more intuitive for the colour components (red, green and blue) to be varied linearly in the computer, the actual voltages sent to the monitor by the display hardware must be adjusted in order to make the colour component intensity on the screen proportional to the value stored in the computer's display memory. This process is most easily achieved by a dedicated module in the display hardware which simply scales the outputs of the display memory before sending them to the digital-to-analogue converters.

More expensive graphics cards and workstations (particularly those used for CAD applications) will have a gamma correction facility.

In combination with the "white-point" gamma correction is used to achieve precise colour matching.

Robert Berger's explanation of monitor gamma.

["Digital Imaging in C and the World Wide Web", W. David Schwaderer].
This article is provided by FOLDOC - Free Online Dictionary of Computing (foldoc.org)

gamma correction

An adjustment to the light intensity (brightness) of a scanner, monitor or printer in order to match the output more closely to the original image. A gamma correction imposes the complement of the "tone curve" in order to flatten the line and bring the gamma closer to the ideal 1.0 (see gamma).
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References in periodicals archive ?
In contrast, Gamma correction which detects the dark part and light-colored part in the image signal and edits the image's Gamma curve is a pixel-based nonlinear transformation, hence the image contrast is enhanced.
Chiu, "Efficient contrast enhancement using adaptive gamma correction with weighting distribution," IEEE Transactions on Image Processing, vol.
In the previous test, the effect of the Gamma correction has been proved.
Gamma Correction. The image generated from medical X-ray machine generally requires gamma correction processing, so as to make it meet the display characteristics and to be easy to the human eye for observation.
The HX8352 also features RGB separated gamma correction. As the R, G, B gamma curves are independently corrected, the colors would be more accurately and precisely presented.
It also offers progressive scan, backlight compensation, gamma correction, a signal-to-noise ratio of 48 dB, and a slow shutter speed.
In performing these encodes and transcodes, Rhozet offers the usual mix of video and audio filtering, along with deinterlacing, cropping, color correction, gamma correction, and other effects.
It comes equipped with three separate image inputs along with a new image processing system containing Auto Picture Control, Dynamic Auto Gamma Correction, and a new Vertical Horizontal Edge enhancement process.
The NVIDIA Quadro FX 4000 SDI graphics-to-video-out solution performs real-time rendering, high-precision video color conversion, and gamma correction. A dedicated video backend unit, complete with analog and digital house sync capability, ensures high-quality SDI video signal formatting and transmission.
General image processing functions such as gamma correction, color interpolation, color correction, color space conversion, auto exposure and auto white balance are implemented on the sensor to enhance and sharpen images.
The CP-S420 offers 2,700 ANSI lumens, a 400:1 contrast ratio for colorful image quality, an operating noise level of 36 dB, Motion Adoptive Progressive Scan for reduced fuzziness in fast-moving objects, and Digital Gamma correction to alter darkness and light levels.